Sadly, another mass shooting has been in the news recently — this one occurring not in a Colorado movie theater, but in a Wisconsin house of worship.

A gunman identified as Wade Michael Page entered a Sikh temple (technically known as a gurdwara) in the Milwaukee suburb of Oak Creek and opened fire, killing six and critically wounding four others, before being shot by police.

One of the critically wounded survivors was a policeman, responding to an emergency 911 call. The victims who did not survive the attack were all Sikhs.

The local community has responded compassionately, with many area residents reaching out to support their grieving Sikh neighbors. Hundreds turned out to attend a candlelight vigil, in remembrance of the victims. Sikhs and non-Sikhs alike across the country — and beyond — expressed outrage at the tragedy, and offered support both for the gunman’s victims as well as for the wider Sikh community.

President Barack Obama even called Manmohan Singh, the prime minister of India, to express his condolences. Prime Minister Singh is himself a Sikh.

Of course, for a fairly sizable percentage of their non-Sikh supporters, Sikhism itself may be something of a question mark — if not an outright “blank page.”

Many Americans have simply never heard of Sikhism. Many more may have heard of it, but know little about it. Some erroneously confuse Sikhs with either Hindus or Muslims, perhaps in part because many Sikh males wear traditional beards and turbans as badges or symbols of their own unique faith.

Who are Sikhs? What is Sikhism?

Sikhism is actually the fifth-largest religion in the world (after Christianity, Islam, Hinduism, and Buddhism). It’s also the youngest of the major world faiths, originating in the Punjab region of India in the 15th century AD.

The term Sikh literally means “disciple.” Sikhs are disciples of a line of ten consecutive Sikh gurus, a line that began with Guru Nanak (1469-1539), who founded the Sikh religion. That line ended with the death of their tenth leader, Guru Gobind Singh (1666-1708), who declared that after his death the Sikh community would henceforth be led not by a living human guru, but by the Sikhs’ holy book, known as the Adi Granth.

That this deeply revered scripture is regarded by Sikhs as the very embodiment of the spirit of their ten human gurus is underscored by the fact that this sacred text is also referred to by Sikhs as the Guru Granth Sahib.

In contrast with the many gods and goddesses of the Hindu faith that dominates India as a whole, Sikhism is staunchly and uncompromising monotheistic, affirming belief in one sole supreme God. On the other hand, like Hinduism (and like Buddhism and Jainism, which are also of Indian origin), Sikhism also accepts karma and reincarnation as metaphysical realities.

In the Sikh view, human beings are born, die, and are reborn, over and over again on this earth; the circumstances of each successive birth are the result of one’s deeds in previous lives (karma), and this cycle of rebirth repeats until one achieves liberation from it by attaining salvation, which Sikhs understand in terms of achieving union with God.

Although Sikhism is the world’s fifth-largest religion, it comes in as a rather distant fifth; the global Sikh population numbers only somewhere around perhaps 25 to 30 million (estimates vary). Most still live in the Indian state of Punjab, with the rest scattered worldwide. Between 250,000 and 500,000 Sikhs live in the U.S. (again, estimates vary).

Unfortunately, this is not the first time in recent history that Sikhs have been targeted as victims of violence. Since 2001, there have been up to 700 attacks upon Sikhs.

The gunman at the Wisconsin gurdwara allegedly had white supremacist ties. The FBI is investigating the shooting as a possible domestic terrorism case, and the Southern Poverty Law Center reportedly described the killer as a “frustrated neo-Nazi.”

As articles of faith, Sikhism affirms the supreme sanctity of human life, the equality of all human beings (including all races, all castes, and both genders), and the duty to engage in compassionate service and to combat injustice.